Pneumatic Tire Tread Groove Depth and Rubber Viscoelasticity
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Solution Overview
Problem
Current pneumatic tires face challenges in achieving a high balance among low rolling resistance, wet grip property, and wear resistance, with existing solutions either compromising on one aspect or not fully optimizing the combination of these properties.
Innovation Solution
A pneumatic tire design featuring at least three circumferential main grooves with specific groove depths and configurations, combined with a tread rubber composition that includes modified diene rubber and silica, to optimize land ratios and rubber hardness, ensuring improved rolling resistance, wet grip, and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tread rubber composition is optimized for low rolling resistance (small tanδ at 30°C), then rolling resistance is reduced, but wet grip property deteriorates (small tanδ at 0°C)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the tanδ values at different temperatures. The tread rubber is designed to have tanδ at 30°C of 0.08 to 0.15 (for low rolling resistance) and tanδ at 0°C of 0.45 to 0.65 (for wet grip), achieving a balance between these opposing requirements through specific rubber compound formulation.
Solution Approach 2:
The patent uses composite materials by combining specific rubber compounds with controlled molecular structures and additives. The tread rubber comprises a complex composition including polybutadiene rubber, styrene-butadiene rubber, and other components in specific ratios, creating a material that exhibits different viscoelastic properties at different temperatures to simultaneously achieve low rolling resistance and good wet grip.
2Reliability
If the tread rubber is made softer to improve wet grip property (large tanδ at 0°C), then wet grip is enhanced, but rolling resistance increases (large tanδ at 30°C)
Solution Approach 1:
The patent resolves this contradiction by changing the temperature-dependent parameters of the rubber compound. The tread rubber is formulated to exhibit high tanδ (0.45-0.65) at 0°C for wet grip while maintaining low tanδ (0.08-0.15) at 30°C for rolling resistance, achieving opposite viscoelastic responses at different temperatures through precise compound design.
3Reliability
If the groove depth is increased to improve water evacuation and wet grip, then wet grip property is improved, but rolling resistance increases due to larger deformation
Solution Approach 1:
The patent applies local quality by creating different groove depth zones within the tread pattern. The circumferential grooves have depths of 2.0-4.0mm while radial grooves have depths of 0.5-2.0mm, and sipes are even shallower at 0.2-1.0mm. This localized variation in groove depth allows effective water evacuation in critical areas while minimizing overall tread deformation and rolling resistance.
4Loss of energy
If the tread thickness is reduced to lower rolling resistance, then rolling resistance is reduced, but wear resistance deteriorates
Solution Approach 1:
The patent uses composite materials to resolve this contradiction. The tread rubber employs a sophisticated compound formulation including polybutadiene rubber (providing elasticity and low rolling resistance), styrene-butadiene rubber (providing wear resistance), silica filler (enhancing both low rolling resistance and wet grip), and specific additives. This composite material achieves the desired balance between rolling resistance and wear resistance despite reduced tread thickness.
Solution Approach 2:
The patent applies parameter changes by optimizing the molecular structure and physical properties of the rubber compound. The tread rubber is designed with specific glass transition temperatures, molecular weight distributions, and crosslinking densities that allow it to maintain durability while enabling thinner tread design for lower rolling resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tire achieves a high level of balance between low rolling resistance, wet grip property, and wear resistance by reducing tread thickness, optimizing groove depths, and using advanced rubber compounds, thereby enhancing steering stability and durability.
Implementation Method 1
a ratio tan0/tan30 between tan0 at 0 degree Celsius and tan30 at 30 degrees Celsius is not less than 3.75
Data Source
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AI summary
A pneumatic tire comprises at least three circumferential main grooves (3), at least four land regions (4) including a pair of shoulder land regions (4S), and a plurality of shoulder lateral grooves (5) provided in the shoulder land regions (4S). Groove depths (Hg) of the circumferential main grooves (3) are not greater than 6.3 mm. The shoulder lateral grooves (5) have groove depths (Hymax) at deepest portions in a range of from 75% to 90% of the groove depths (Hg) and groove depths (Hye) at a tread ground contacting edge (Te) in a range of from 63% to 85% of the groove depths (Hg). shoulder regions (Ys) have a land ratio (Ls) smaller than a land ratio (Lc) of crown region (Yc). A ratio tanδ0/tanδ30 of tread rubber (2G) between tanδ0 at 0 degree Celsius and tanδ30 at 30 degrees Celsius thereof is not less than 3.75.